1. Field of the Invention
The present invention generally relates to electrical equipment and, more particularly, is concerned with an electrical receptacle assembly employing components in an enhanced heat dissipation arrangement.
2. Description of the Prior Art
Heretofore, single and duplex electrical receptacles manufactured and marketed by Hubbell Incorporated of Orange, Connecticut, the assignee of the subject application, have employed a generally rectangular housing with plug contact receiving openings formed on its front side and a generally U-shaped "wrap-around" mounting bridge positioned adjacent the rear side of the housing and extending vertically therealong and forwardly therefrom along top and bottom ends of the housing. The mounting bridge at a back portion is in contact with the rear side of the housing. Also, the mounting bridge has upper and lower mounting tabs attached to and extending respectively upwardly and downwardly from front ends of opposite upper and lower end portions of the mounting bridge. The upper and lower mounting tabs have eyelets defined therethrough for fastening the bridge to a receptacle or outlet box, which is attached to a building wall, by the use of screws inserted through the upper and lower eyelets and threaded into the box.
One specific group of electrical receptacles, manufactured and marketed by the assignee of the subject application, are called surge suppression receptacles. These receptacles are typically used with voltage transient sensitive electronic equipment, such as computers and the like, which need steady uninterrupted A.C. power in order to function properly. The suppression of overvoltages or spikes frequently received by these receptacles is provided by the use of voltage clamping devices, which may take the form of one or more metal oxide varistors (MOVs). The varistors are incorporated in a circuit provided in the receptacle between the utility power connection wires and the plug-in contacts of the receptacle. The circuit is normally not affected by the presence of the varistors. However, in the instance when a voltage transient above the MOVs voltage rating is encountered, the varistors absorb the excess power and thereby instantaneously reduce or clamp down the voltage of the A.C. power, allowing only a safe, acceptable level thereof to pass through the receptacle to the electronic equipment.
The absorption of excess electrical power by the varistors causes them to increase in temperature. Typically, the varistors are mounted to a circuitboard in the receptacle on a side of the circuitboard where other electrical components are mounted and opposite from a reverse side where solder connections are made between circuit paths thereon and the ends of the leads of the components extending through the circuitboard. As their temperatures increase, the varistors will conduct heat to the circuitboard and radiate heat to adjacent electrical components. Established requirements pertaining to thermal stress on devices containing varistors intended for suppression of surge conditions provide that the heat generated by the varistors must be dissipated in some manner. Heretofore, the plastic material of the receptacle housing also functioned as a heat sink to dissipate excess heat generated by the varistors. However, the receptacle housing has not been entirely satisfactory for this purpose. Heretofore, the "wrap-around" mounting bridge which, as mentioned above, is used on single and duplex electrical receptacles as the means to attach the receptacle to an outlet box, had not been incorporated by the specific group of receptacles which had the added function of surge suppression.
Consequently, a need still exists for improvements in the design and construction of an electrical surge suppression receptacle assembly which will provide improved dissipation of heat from the varistors thereof.